Lesson 12.3: Science Connection

On Thin Ice

Earth's glaciers are quickly melting and falling apart. Scientists say that within 15 years, the glaciers that cover the top of Africa's highest mountain will be gone.

Mount Kilimanjaro, in the African country of Tanzania, is known for its breathtaking scenery. At the base of the mountain lies a lush jungle where elephants, antelopes, and tigers roam.

High up, the mountain is cold, snowy, and desolate. Very few animals or plants live near the top. Still, people from all over the world travel to Tanzania to climb to the snowcapped peak of Kilimanjaro, the tallest mountain in Africa.

Kilimanjaro is a majestic sight. In 1938, Ernest Hemingway wrote in his story “The Snows of Kilimanjaro,” “...as wide as all the world, great, high, and unbelievably white in the sun, was the top of Kilimanjaro.”

But Kilimanjaro has changed since then. Some scientists say that by 2018 there will be no snow on Kilimanjaro. The glaciers that cap the mountaintop are quickly melting. Glaciers that were measured as covering 4.8 square miles in 1912 have now shrunk to less than one square mile.

“I expected to be walking through snowfields,” said a British tourist who recently climbed Kilimanjaro. “But there was no snow cover at all.”

Kilimanjaro's glaciers aren't the only glaciers that are melting. From Antarctica to Glacier National Park in Montana, the slow-moving masses of snow and ice are shrinking at an alarming rate.

Scientists say that while most of Earth's 160,000 glaciers have been thawing naturally for centuries, the melting has gotten worse since the 1990s, the hottest decade in a thousand years. They believe that glacial melting is a telltale sign that Earth has gotten warmer. They fear that the melting glaciers will threaten human, animal, and plant life within the next century as ocean levels rise by as much as 12 to 24 inches.

Antarctica on the Edge

The problem is most severe in Western Antarctica, where, 30 years ago, scientists noticed that glaciers were pulling a disappearing act. Scientists say that Antarctica's glaciers have lost 36 cubic miles of ice in the past decade. And that's just in Antarctica! But the additional water is enough to raise the world's sea levels by about one-sixtieth of an inch.

Consider this: If, in the future, ocean levels rise one foot, the additional water would cause widespread flooding along the world's coastlines, submerging coastal cities such as New York, Boston, and San Francisco.

Glaciers are also melting quickly in South America. In Peru, a glacier named Qori Kalis loses as much ice in one week as it used to lose in a year.

“You can literally sit there and watch it retreat,” said Lonnie Thompson, a glacier expert from Ohio State University.

In South Asia, melting water from glaciers in the Himalayan Mountains is threatening tens of thousands of people who live and work in the valleys below.

Hot Time

Can anything be done to stop the big melt? Perhaps not.

Some say that global warming is a natural phenomenon and that eventually temperatures will get back to normal. But that might take many years.

Others, however, say that humans contribute to Earth's rising temperatures by sending greenhouse gases, such as carbon dioxide and methane, into the atmosphere. Greenhouse gases trap the sun's heat. Over the past 100 years, the trapped heat has raised the world's temperature by 0.5 degrees to 1.5 degrees Fahrenheit.

Scientists say that humans must work to stop the damaging effects of global warming. Only then can the glaciers, and the rest of us, be saved.

glacier:

Large sheet of very slowly moving snow and ice: As glaciers flow downhill, they erode mountains and create valleys.

lush:

Thick, green growth: After the rain, the lush lawn sparkled in the sun.

desolate:

Place where there are no people: In July, the schoolyard was desolate.

submerge:

Cover with water: Most of the bath toys floated, but one was submerged in the tub.

retreat:

To go backward or fall back: When it began to rain, we retreated from the beach.

phenomenon:

Event that can be explained scientifically: I find it hard to believe that a beautiful rainbow is a natural phenomenon.

Although Kilimanjaro is near the equator, where it is very hot, the temperature on the mountain peak can be very cold. The temperature at the top ranges from as low as -25°C just before dawn to about 5°C in the heat of the morning sun.

Suppose a worker at Kilimanjaro National Park needs to make a sign for visitors showing the low and high temperatures on the mountain in degrees Fahrenheit. He would convert -25°C and find it to be equivalent to -13°F!

Then he would convert 5°C to °F using this formula: F = C + 32.

Here's how:
F = C + 32
= (x5) + 32
= (x) + 32
= 9 + 32
= 41

The morning temperature of 5°C at the top of Kilimanjaro is the same as 41°F.